Schlitz-basierter Analysator für Strahlausbreitung M²
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|By adding the capabilities of the NanoScan to the ModeScan, the range of possible measurable lasers is greatly expanded and the speed of the measurements dramatically improved. The NanoScan’s software controlled variable scan speed allows the measurement of both CW and kHz pulsed lasers with any NanoScan scan head, covering the entire wavelength range from UV to FIR. The NanoScan’s rapid beam finding and autoranging speed up the total M2 measurement to ~20 seconds for CW lasers. Both 200mm and 400mm lenses are available to generate the proper artificial waist for the laser source under test. For ease of alignment, there is an entrance iris on the optical axis of the NanoModeScan and a precision alignment stage for horizontal and vertical positioning.
The ISO 11146 Method
The ISO 11146 method for measuring the propagation of a laser source calls for the measurement of the beam diameter for at least 10 positions through the waist created by a test lens inserted in the beam path. Five locations should be within ±1 Rayleigh range of the artificial waist and at least five more points beyond two Rayleigh ranges from this waist. These measurements are then used to compute the laser propagation parameters. Once points are selected properly, the ISO Method is the fastest measurement method and best for volume testing of lasers.
The Rayleigh Method
The ISO method requires the user to manually select the measurement points, and changing one or two of the selected points can yield different M2 values. The Rayleigh method is completely automated, selecting its own measurement points based on mapping the Rayleigh range of the beam waist. This method is fully discussed in Application Note 230, Fast M2(k-factor) Measures with Photon Beam Profilers. In addition, the Rayleigh method can yield more consistent results for M2 values for lasers that are not exactly like those for which the ISO standard was written, such as fiber lasers, lensed diode lasers, and VCSELs.
The NanoScan Difference
With the NanoScan-equipped NanoModeScan, all scan heads can measure pulsed beams with repetition frequencies down to 10kHz. Measuring pulsed beams in discussed in the application note Measuring Pulsed Beams with a Slit-Based Profiler. The silicon and germanium detectors will measure less than a milliwatt of power. The pyroelectric detector-equipped NanoScan head can analyze higher power lasers at all wavelengths. The increased dynamic range of the NanoScan enhances the signal to noise ratio of the system and allows a much broader range of laser powers to be analyzed with one instrument setup.
Real-Time Divergence Measurement
By monitoring the divergence angle θ, it is possible to make a measurement that will be directly proportional to M2. This enables the adjustment of the laser performance in real time at the NanoScan’s rapid update rate (up to 20Hz). To use this feature, the scan head is moved to a position one geometric focal length from the test lens. Divergence is the beam diameter divided by the focal length, and the measured divergence is equal to M times the embedded divergence.
Therefore when the beam diameter at this location is minimized, the divergence is at its minimum and the M2 of the laser should then be optimized. After this real-time adjustment, the full M2 measurement can be done to generate the required parameter values. This method makes the NanoModeScan an even more valuable tool for the final setup of lasers on the manufacturing floor by decreasing the time it takes both to adjust the laser system and to make the measurements required for quality control documentation. Alignment
|Scan head Travel||500mm|
|Optical Axis Height||140-170mm|
|Standard Lenses||200mm EFL, BK-7 plano-convex, Broadband AR Coated
400mm EFL, BK-7 plano-convex, Broadband AR Coated; UV through long IR lenses available
|Optional Lens||200mm FL fused silica for UV coated for wavelength of use
350mm FL fused silica for UV coated for wavelength of use
190mm FL IR lens for 10.6μm wavelength
|Minimum Spot Size||See scan head specifications|
|Source Power||See scan head specifications|
|File Saving and Data Logging||Data files, ASCII Files|
|AC Power||110V, 60Hz standard
220V, 50Hz optional
|Communication||RS-232 Interface or USB to RS-232 adapter required|
|Mechanical (Dimensions in mm)|
|NanoModeScan Linear Stage||812 × 102 × 78|
|Photon Motion Controller||273 × 89 × 57|
|Removable Light Shield||787 × 777 × 110|
|NanoModeScan Linear Stage||8.4kg|
|Photon Motion Controller||1.5kg|
All NanoModeScan Systems include (unless otherwise noted):
- High-resolution scanhead with rotation mount.
- Two BK 7 lenses and mounts. Standard are 200 and 400mm focal length.
- Lens coating Choices:
- VIS Visible: 430–700nm (not for use with Germanium detector)
- NIR Near IR: 650–1000nm
- LIR Long IR: 1000–1550nm (not for use with Silicon detector)
- VֺֺLIR: Very long infrared >1550nm. The two glass lenses will not be included but instead credited toward the very long wavelength IR lens or lenses that will require an optional charge (for use with NMS-NS2-Pyro/9/5 only).
- OPTIONAL UV: If ultraviolet application, the two glass lenses will not be included; instead we will send one 200 mm focal length lens coated for wavelength of use.
Be sure to specify XXX wavelength when ordering.
|NanoModeScan M² Systems|
|NMS-NS2-Si/9/5||Model 1740 ModeScan with NanoScan 2 Silicon (Si ) Detector 9mm aperture 5μm slits Si detector, 63.5mm diameter head, 9mm entrance aperture, and matched pair of 5.0μm wide slits. Use from 190 to 1000nm wavelengths.||PH00448|
|NMS-NS2-GE/9/5||Model 1740 ModeScan with NanoScan 2 Germanium (GE) Detector 9mm aperture 5.0μm slits. Germanium detector, 63.5mm diameter head, 9mm entrance aperture, and matched pair of 5.0μm wide slits. Use from 700nm to 1.8μm wavelength.||PH00449|
|NMS-NS2-Pyro/9/5||Model 1740 ModeScan with NanoScan 2 Pyroelectric Detector 9.0mm aperture 5μm slits. Pyroelectric detector, 63.5mm diameter head, 9mm entrance aperture, and matched pair of 5μm wide slits.||PH00450|
|MSP-NS-Pyro/20/25||Model 1740 ModeScan with large aperture NanoScan1 scanhead with 20mm Pyroelectric Detector, 25um slits 100mm diameter head, 20mm entrance aperture and matched pair of 25um wide slits.||PH00218|
|LENS 200 UV-XXX||Optional 200mm quartz lens for use between 190–400nm wavelengths.||PH00090|
|LENS 400 UV-XXX||Optional 400mm quartz lens for use between 190–400nm wavelengths.||PH00091|
|LENS 190 10.6||Optional 7.5-inch focal length lens for use at 10.6μm wavelength.||PH00092|
|LENS 100 VIS||Optional 100 mm focal length lens for use 400–700nm wavelength.||PH00093|
|LENS 100 NIR||Optional 100 mm focal length lens for use 650–1000 nm wavelength.||PH00094|
|LENS 100 LIR||Optional 100 mm focal length lens for use 1000–1550nm wavelength.||PH00095|
|1740 LENS MNT||Lens mount for users wanting to use their own 25mm diameter lens.||PH00075|
|Model 1740||ModeScan Rail w/o scan head, small scan head||PH00447|
|1740 LENS PREP||ModeScan custom lens||PH00076|
|Lens 400 2um||Optional 400mm focal length lens for use at @2μm wavelength||PH00224|
|Lens 200mm VIS||Optional 200mm focal length lens for use 400-700nm wavelength||PH00237|
|Lens 400mm VIS||Optional 400mm focal length lens for use 400-700nm wavelength||PH00238|
|Lens 200mm NIR||Optional 200mm focal length lens for use 650-1000nm wavelength||PH00239|
|Lens 400mm NIR||Optional 400mm focal length lens for use at 650-1000nm wavelength||PH00240|
|Lens 200mm LIR||Optional 200mm focal length lens for use at 1000-1550nm wavelength||PH00241|
|lens 400mm LIR||Optional 400mm focal length lens for use at 1000-1550nm wavelength||PH00242|